Popular culture has affected the way Americans see and understand espionage. But beyond the fantasy of the spy genre, the truth is that spies aren't really as exciting as people think.

That doesn't mean they're not impactful, but many Americans don't really seem to understand the extent of that impact.

Espionage — and specifically Russian espionage — has been the topic of great national security concern since the Cold War.

"Once upon a time, spying or espionage was a fairly straightforward game," said the host of the 1965 government-funded film "Science of Spying." "It's not just stealing military hardware and secret plans, but using tanks and planes and men to promote our policies around the world and sometimes to overthrow governments we don't like. Both sides in the Cold War do it. Both sides deny it."

Some of the information passed to the Soviet Union included the identities of overseas U.S. intelligence agents and information on the atomic bomb.

The FBI is now accusing Butina — who hasn't registered as a foreign agent on U.S. soil — of using ties to gun rights organizations and a Republican operative to influence the GOP to be more sympathetic of Russia. Butina pleaded not guilty and is now being held without bail.